Technical Field of the Invention
The present invention relates to a method and apparatus for detecting a vehicle running in a blind spot of the vehicle, and a method and apparatus for giving a warning when changing cruising lane.
Related Art
It is well known that an inner rearview mirror (rearview mirror) and outer view mirrors (door mirrors or fender mirrors) in a vehicle can have a blind spot that corresponds to a rearward area on the left or right side of the vehicle. For detecting a vehicle running in such a blind spot and for calling attention of the driver to this, a patent document JP-A-2000-214256, for example, suggests an apparatus for detecting a vehicle running in a blind spot. According to this apparatus, the driver can notice the presence of a vehicle which is running in the blind spot and has a possibility of inviting a collision in changing cruising lane. This apparatus is able to eliminate the driver's uneasiness when the driver changes lanes.
The apparatus for detecting a vehicle running in a blind spot disclosed in the above patent document detects the position of a nearby vehicle on the basis of the parallax of images picked up by a plurality of CCD (charge coupled device) cameras installed in the vehicle equipped with the apparatus. The above patent document also discloses use of a laser radar or a milliwave radar sensor to detect a vehicle that runs in a blind spot.
The milliwave radar may be used for configuring a blind spot warning (BSW) device to detect a vehicle that runs in a blind spot and to warn the driver of the presence of the vehicle. With this configuration, the vehicle which runs in a far distance in a blind spot can be detected with high accuracy.
However, detection of a nearby vehicle (hereinafter referred to as “target”) using a milliwave radar raises a problem that the range of high-accuracy detection is limited. For example, the accuracy of detection is high only in a predetermined angle range as viewed from the milliwave radar. In other words, high detection accuracy is ensured for a target far from the milliwave radar, while the accuracy of detection is low for a nearby target.
The blind spot of a driver may very often extend over a wider range exceeding the range in which high detection accuracy of the radar is ensured. For this reason, there is a concern that the driver may be informed of a detection position of a target, which has a large difference compared to the actual position of the target.
It is thus desired to provide an apparatus being suitable for detecting other vehicles running in a blind spot, the apparatus exerting high detection accuracy in an actual blind spot, and to provide an apparatus being suitable for giving a warning in changing cruising lane to a driver.